Some things in life are simple: we know that two pieces of bread with stuff between them, for example, is a sandwich. Swap in a long roll, however, and things get a lot more complicated.
Let’s start with the submarine, or sub. A sub is at least six inches long and is constructed with a combination of meat, cheese, fixings (lettuce, tomato, etc.), and dressing. It is usually served cold. According to Google Trends, the word "sub" is by far and away the most commonly used of today's four large-sandwich terms. You can see this in the graph below:
Looking at the regional breakdown, "sub" is also clearly the winner—except for one, lonesome state.
Pennsylvania—what is going on??
Pennsylvanians—Philadelphians, in particular—have their "hoagies." A hoagie is just a sub—the Oxford English Dictionary literally defines it as a "submarine sandwich"—but the Pennsylvania folk have insisted on making it their own. According to Bon Appétit, the term likely comes from Depression-era jazz musician and sandwich-shop owner Al De Palma, who started calling his submarines "hoggies" because you "had to be a hog" to eat a sandwich that big. (So judgy!) "Hoggies" somehow morphed into "hoagies," and you got yourself a regional sandwich term.
Head over to New York City, and you’ll see a similar sandwich referred to as a "hero." The term likely comes from New York Herald Tribune columnist Clementine Paddleworth (yes, that was her name), who in 1936 described a sandwich so large "you had to be a hero to eat it." More so than a sub, a hero can refer to both hot and cold sandwiches, which is why you’ll see things like meatball heroes and chicken-parm heroes on menus around the area.
Lastly, we have grinders, which is the New England–based term for a hero. According to Bon Appétit, "some claim that it was named for 'grinders,' Italian-American slang for dockworkers (who were often sanding and grinding rusty hulls to repaint them)," but the term most likely comes from the fact that they were harder to chew than normal sandwiches: "that toothsomeness got translated into 'grinder,' since that's what your teeth had to do to get through a bite."